[Feature Request] Add `--dry-run` to the `aptos update` command

[mkurnikov]

🚀 Feature Request

Motivation

Is your feature request related to a problem? Please describe.

I would be great to check whether the update for the CLI is possible without actually calling the command and getting into the interactive mode.

Pitch

Describe the solution you'd like

aptos update aptos --dry-run which outputs

{ "Result": "Already up to date (v3.3.0)" }

or

{ "Result": "Update is available (v3.4.0)" }

Describe alternatives you've considered

Calling current aptos update and parsing the output to extract new version.

Are you willing to open a pull request? (See CONTRIBUTING) Maybe later.

Additional context